436 



MEDUS-ffi OF THE WORLD. 



According to Maas, if the egg be cut into two when in the 2-cell stage, each cell finally 

 develops into a small, normal planula and medusa. If the 8-cell stage be separated into a 



«w.w 



exnr 



Fig. 286. — Solmaris fiavescens. Interradial section, drawn by the author, at Naples Zoological Station. 



em, cord of entoderm at the bell-margin. e*,exumbrella. exnr, exumbrella nerve-ring, gon, male gonad, st, central 

 stomach, su, subumbrella. v, velum. Ectodermal nuclei are shown in solid black and entodermal nuclei are 

 represented as circles. 



piece with 4 small and another with 4 large cells, the large-cell piece develops irregularly and 

 the small cells degenerate. A meridional cut through the 8 or 1 2-cell stage gives a medusa 

 with only local irregularity. 



288. 288. 



Fig. 287. — Solmaris solmaris (.■Egineta solmaris), after Gegenbaur, in Zeit. fur wissen. Zool., B. 8d. 



Fig. 288.— Solmari s(.Egineta) corona, after Keferstein and Ehlers, 1861. Entire medusa and one of its marginal sense-organs. 



Fig. 289. — Solmaris "coronanlha," after Haeckel, in Syst. der Medusen=S. corona. 



StschelkanowzefF, 1905, has made a further study of the development which would 

 necessitate some modification of the account given by Maas. StschelkanowzefF states that 



